Prognostic significance of Blood Urea Nitrogen in comparison to Creatinine levels in mortality assessment of patients at admission with Acute Coronary Syndrome in Shivamogga district, Karnataka

Introduction and Objectives: Several studies have hypothesized the relation of Blood Urea Nitrogen (BUN) and serum Creatinine level with the severity of coronary artery disease. The basis of this study is to show the prognostic significance of BUN and serum Creatinine levels at admission for assessing the risk of mortality in patients with acute coronary syndromes (ACS). This study also undertakes the comparative prognostic significance of BUN over serum creatinine as an indicator of risk of mortality in patients with ACS. Materials and Methods & Results:This was a prospective study of all patients admitted with suspected (n=1019) and retrospectively confirmed (n=65) Myocardial Infarction (MI) or Unstable Angina. The Receiver-operating characteristic curve analysis established that the area under the curve for BUN was higher than that of Creatinine 0.71 (95% CL 0.65 to 0.78) and 0.63 (95% CL 0.59 to 0.66), respectively (p=0.005). The threshold level was 8.6mmol/L for BUN and 110µmol/L for Creatinine. Sensitivity was 61% and 56% for threshold levels of BUN and Creatinine, and specificity was 84% and 78%, respectively. It is seen only an increase of BUN and a combination of increased BUN and Creatinine levels, as risk factors of mortality with ACS.Isolated increase in creatinine levels was not found to be significant. Separate inclusion of BUN and Creatinine as continuous variables in the regression model showed that both were associated with the risk of mortality. Odds Ratio (OR) 1.18 (95% CL 1.12 to 1.25) and 1.08 (95% CL 1.011 to 1.019) per unit increase (R2 =12.5 and 8.1% respectively). When both were simultaneously included, only the increased BUN level was persistent with the prognosis of ACS: OR after multivariate adjustment 1.14 (95% CL 1.04 to 1.18). Conclusion: An increased level of BUN is a more significant prognostic marker of mortality assessment at admission in ACS than that of serum Creatinine.